Wall Insulation for New Construction, Series 5-10

Typically, this is a wood-frame wall with the potential for insulation in the stud cavity (batts or spray-applied) and on the exterior face of the studs (rigid insulation). See Figure 1. During planning and installation, note the following:

• The vapour retarder should be at or near the inside surface of the insulation and would most commonly be 6 mm (0.2 in.) polyethylene sheeting at the inside face of the studs or vapour-retardant paint on the finished drywall.
• The air barrier can be provided by the polyethylene vapour retarder, by the interior drywall or by air-barrier sheeting on the exterior face of the studs. In all cases, the air barrier must be carefully detailed to be continuous at all penetrations.
• Adding rigid (board-stock) insulation to the outside face of the studs minimizes thermal bridging. Spacing the studs at 610 mm (24 in.) rather than 406 mm (16 in.) where possible will also reduce thermal bridging.